1. Division of General Internal Medicine and Health Services Research, Department of Medicine, David Geffen School of Medicine, and Department of Health Policy and Management, Fielding School of Public Health, University of California, Los Angeles, Los Angeles, California (L.E.W., J.G.E.)
2. Departments of Medicine and Emergency Medicine, University of Washington Harborview Center for Prehospital Emergency Care, University of Washington, Seattle, Washington (G.N.).